This invention relates to preparation of substituted alkoxy and acyloxy furans using as starting materials butenolides. Prior to this invention there has been no reasonable synthetic method for the general preparation of alkoxy furans or acyloxy furans. Often such compounds have been painstakingly and meticulously isolated from natural sources. This is very expensive, time consuming and does not provide significant product yields.
As those skilled in the art know and understand, furan compounds are those which contain at some point in the compound's structure the following common nucleus: ##STR1## Such furan ring containing compounds are valuable presursors for the preparation of a wide variety of biologically active compounds. They can, for example, be successfully used as the starting point for preparation of complex butenolides, of other substituted furans, and they can be used for the making of such biologically active compounds, such as lycorine which is an anti-bacterial agent whose structure represents a challenge to present methods of synthesis, gibberelic acid, which is an important plant growth regulator that is not easily available from natural sources, and protoanemonin and its substituted derivatives, among others. In short, the number of desirable biologically active compounds which can be prepared using as a nucleus the furan moiety, is almost limitless. However, the effective utilization of furans as a precursor for preparation the numerous desirable biologically active compounds such as those listed above has met with only limited success and usage in the past. This is so primarily because of the difficulty of obtaining the furan starting materials.
Accordingly, the primary object of this invention is to provide a synthesis process which allows for quick, easy, high yield preparation of furan compounds.
Another object of this invention is to provide a synthetic process for furans which in turn can be used as building blocks for preparing a wide variety of biologically active compounds.
Yet another object of this invention is to provide a synthetic process for furans which uses readily available butenolides as a starting material, which under the conditions of the reactions of this invention, undergo rearrangement to the furan ring.
An even further object of this invention is to provide a process of alkylating butenolides to provide an alkylated furan intermediate which will quickly and easily add an electrophilic agent, under metallating conditions to provide a substituted furan.
The method and manner of accomplishing these objects of this invention, as well as others, will become apparent from the detailed description of the invention, which follows.